Method of forming turning tool holders



y 1930. E. F. G. GIBBS 1,771,709

METHOD OF FORMING TURNING TOOL HOLDERS Original Filed Nov. 24, 1922 E Eta-.5...

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Patented July 29, 191W nn wan:o F-e. GIBBS, on nn'rnorr, iuioniean METHOD OF FORMING TURNING TOOL HOLDERS Continuation of application serial No.602,98i, filed November 24, 1922.

21, 1927. Serial No. 241,620.

This invention relates to new and useful improvements inwhat is known as a turning tool holder, which is held in the tool post of the common enginelathe and other machine tools and which, in turn, holds the inserted cutter-bit or cutting tool. The device manufactured in accordance with this invention is used chiefly in turning, facing and planing of metals. 1 do not mean to limit myself, however, in any sense, except as required by the scope of the claims.

The objects sought in this invention are to produce a one-piece holder of maximum strength; the construction of which will suggest short hold, to the unthinking operator; which will enable the use of inserted cutters of indefinite lengths; give them the proper angle or inclination; facilitate the production of a good cutter-seat and facilitate economy and protection in its manufac ture.

I attain these objects by the construction hereinafter described, illustrated in the ac companying drawings, which form a part 5 of this specification, and then specifically defined in the appended claims.

Referring now to the said drawings by figures Figure 1 is a side elevation of the too] 3011010161 complete, with the cutting tool in working position.

Figure 2 is a plan view of the tool holder alone.

Figure 8 is a sectional view of the finished holder, (for square cutters) from the rear,

on the line 3, 3, of Figure 1.

Figure 4 is a sectional view of the same, on line 4, 4:, of Figure 1.

Figure 5 is a sectional view of the same,

so on line 5, 5, of Figure 1.

Figure 6 is a rear end finished holder.

Figure 7 is a sectional view of the finished holder, (for rectangular cutters) from the rear, on line 3, 3, of Figure 1, and

Figure 8 is a bottom view of the holder alone.

Reference now being had to the drawing by letter, in which similar letters refer to so similar parts throughout the several views,

outline of the un a designates the one-piece holder proper; 7) the fiat section of the horizontal bearing surface for the tool post screw; 0 the convex section of same; (Z designates first the major channel hole or bore and later the elongated rear section of the internal cutter-holding channel; a the neat fitting rectangularconstricted front section of the same; f the cutter bit or cutting tool; 9 the rib or bulge on each side of the original forging, which afterwards is pressed in, or down; 7i thecutter clamping set screw; 2' the two slight depression lines on each side of the holder; and the flat bottom bearingsurface of the holder.

It is to be seen from Figs. 1,2 and i, that the central section b of the, holders top sur- This application filed December face, on which the tool post screw bears is 7 horizontal and flat, while the rear section ,0, of the same is convex. It is also seen from Figs. 1 and 6 that section b is higher than section 0. The reason for thus differentiating the forms of the said two sections, and placing the preferable one in front, is to re.- mind and induce the unthinking operator to set the holder as far back in the tool post as possible, in order to make it asrigid as possible.

It is also to be seen that the internal cutter-channel, (Z and e, which carries the rectangular cutter to which it is adapted, is tubular and runs the entire length of the straight one-piece holder; both terminals of which are wholly within the respective ends of the said holder; leaving its flat bottom bearing surface an unbroken plane.

This centrally disposed channel weakens the holder least, enables the use of cutters of indefinite lengths, and reduces the inclinas tion ofthe cutting tool to about five degrees, the proper angle.

The advantageous features mentioned in the foregoing sentence, as well as economy in manufacture and good cutting tool seats are made practical by the peculiar steel forgings shape and manner of which and in which this holder is made. comes with a temporary rib or bulge 9,011 both sides from the rear end up to its head, The major hole (Z is first drilled from the said rear end, concentrically between the said ribs The said forging up to'the said head; or about three-fourths its entire length. The hole or bore thus obtained is just about lar e enough for the proposed cutting tool, ifsquare, to slip in with very little, if any, breaching, but the side walls are thus partially cut away. The bore is extendedby running a smaller or constricted bore 6 through the head, or about one-fourth of the entire length. When this constricted bore is broached out to neatly screw it, the major bore elongated in the cross section, leaving straight vertical side walls, and we eliminate about three-fourths of th' expensive broaching.

Furthermore the cutters now used are square but the rectangular cutter, proportioned 1 to 1, is preferred to the simple square one, but the cost of elongating the channel therefor, by broaching is prohibitive; 'whereas by this process it is easily done.

When thesaid ribs are pressed down the holder lying fiat, the rear end of the holder spreads out, but it cannot spread out up at the head because it is tied by the metal in the head. Therefore the major portion of the channel, (now elongated) tapers gradually vertically, being deepest at the rear end, as shown in Figs. 1, 4t, and 5, and it makes more room for bent cutters or cutting tools where room is needed. 7

All holders made by this process carry a distinguishing mark, a natural trade-mark, so to speak, in two slightly depressed bending lines, 2', or a double bending line on each side, formed by bending the metal when the ribs are pressed down. They run from the rear end parallel with the channel and ap parently unite at the head.

This application is a continuation of my appllcation for improvements in turning tool holders, serlal No. 602,987, filed November I submit the following claims:

1. The methodof forming a turning tool holder which comprises forging abody of metal into approximately final external shape and provided with a longitudinal rib or bulge on each side of said body extending throughout a portion of its length, forming Having thus fully described my invention,

a longitudinal bore from end to end of said body'and concentric with said ribs, the portion of said bore which is co-extensive with the rlbs being of larger diameter than the remaining portion, broaching the remaining portion to fit a rectangular cutter, and finally holder which comprises forging a body of metal into approximately final external shape and having a longitudinal rib or bulge on eachside thereof, drilling a longitudinal hole from one end of said body toward the other on a line concentric with said ribs to form a cutting tool receiving boredrilling a reduced continuation of said bore extending out of the other end of the body, and flattening said ribs to make the distance between the side walls of the large bore equal to the diameter of the reduced continuation.

3. The method of forming a turning tool holder which comprises forging a body of metal into approximately final external shape with a longitudinal rib or bulge on each side thereof extending throughout a portion of the length of the body, drilling a relatively large hole from one end of the body toward the other on a line concentric with said ribs to form a cutting tool receiving bore, continuing said bore through to the other end on a reduced diameter, broaching this latter part of the bore to receive a rectangular cutting tool without increasing the diameter of the bore, and finally mashing said ribsdown to make the distance betr-reen the side walls of the major bore equal to the distance between the side walls of the small bore.

In testimony whereof I ailix my signatu re.

EDYVARD F-G. GIBBS. 

